Thanks guys
I did connect a spare car battery to bike with jumper wires. Started fine (after carb rebuild/cleaning) then next day it wouldn’t start but will show spark on points. No spark on 1$2 plugs. Checked caps and no resistance. Went to Honda and bought two caps, spark is back. While talking to Honda guy, he said I used car battery and that screwed up my electrical system and potentially this is why my plug caps have gone bad 
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Bike had not started in 3-4 years
I got scared that may have damaged rectifier or coils etc. Since I ran bike like this to sync my carbs.
If you want piece of mind that its your caps are bad, you can always measure the resistance of the spark plug caps. Pre 1976 the resistance is 7ohms, and post 1976 the stock cap is 10K ohms resistance. Aftermarket ngk caps are usually 5 ohms. Caps on the early cb750s are considered burned out at 9ohms, and on the later bikes (like your 1978) 11 ohms. Putting a new lower ohm cap on the later coils won't hurt anything but ngk does make a 10ohm cap if you want to put the right parts on. There is a hondaman post about this that I used checking the caps when I was waking up a cb750 that had sat for 25 years (ran great by the way).
most people I know don't ever check plug cap resistance. Corrosion tends to be the enemy of them, as does sitting around. If they get used they tend to last longer.
edit: found the post
http://forums.sohc4.net/index.php?topic=67096.0if you are worried about damage to your "electrical system", there really is only two kinds of damage that can happen - damage to the charging system components internally, and letting the smoke out of the wires. I am going to assume you would notice the smoke leaving the wires but if you want to check the charging system, get the bike running and put a multimeter on the battery leads to see the output. You want to see the voltage increase as the revs increase and you want to see it stop at right around 14v at redline. if it does that, then all is well.
